The North Talc deposit located 4 kilometres southeast of Pyramid Mountain on a north tributary of Log Creek, 2.5 kilometres northwest of the Talc Lake deposit (092ISW063) (Assessment Report 2265).
Significant talc occurrences were first reported in this area in the early 1950s by Geological Survey of Canada geologists. In 1973, talc was first reported in the Talc Lake prospect area by J.A. Chamberlain Consultants while conducting surveys for nickel, chromite and talc. Low grade nickel (0.2 per cent) was identified over a wide area and a zone of talc-magnesite mineralization was outlined. The zone is now referred to as the Talc Lake deposit. Between 1986 and 1988, 3000 hectares of ground was staked to cover potential talc (magnesite) lenses. In 1989 and 1990, Highland Talc Minerals Ltd. began systematically geological mapping the Talc Lake deposit. Late in 1990, a second talc zone referred to as the South Talc deposit was defined. Four exploratory drillholes were completed in 1990. Between 1991 and 1992, detailed geological surveys, surface stripping, and four follow-up drillholes were completed. In 1992, the North Talc deposit and 5 smaller satellite lenses were discovered. In 1993, a 100-kilogram bulk sample was taken from the South Talc deposit and a 120-tonne bulk sample was taken from the North Talc deposit shipped to Finland for Pilot Scale tests. In 1994, an additional 10 drillholes were completed on the South Talc deposit.
The area is underlain by phyllite, schist and foliated greenstone of the Permian(?) to Lower Cretaceous Bridge River Complex (Group) and by phyllite, schist and local conglomerate of the Upper Jurassic to Lower Cretaceous Relay Mountain Group. Pods of serpentinized ultramafics of the Bridge River Complex occur in fault and normal contact with both units. All units are intruded by stocks of Late Cretaceous quartz monzonite and granodiorite.
The Bridge River Complex and Relay Mountain Group are separated along the ridge by an intervening fault-bounded mass of serpentinite striking northwest for 5.9 kilometres, generally following the crest of the ridge, and varying up to 900 metres in width. The ultramafic rock is dark green to black and weathers buff to reddish brown. The serpentinite consists of fine grained, massive serpentine with minor carbonate and 5 per cent magnetite.
Since 1992, a systematic program was completed on the North Talc deposit that has included geological surveys, bulldozer stripping, trenching and drilling. The deposit consists of a lens of talc on the north side of the lake, which has been exposed over a length of 800 metres and a width of 50 to 150 metres. The talc lens is covered by 1 to 2 metres overburden but has been recently exposed by new logging roadcuts. The deposit is fault bound on its west-southwest side where a thick sequence of phyllite and argillite occur. Serpentinite occurs on the northeast side of the talc deposit.
The talc is pale green to white with a creamy buff weathered surface and contains small quantities of disseminated magnetite.
In 1993, a 120-tonne composite sample was extracted and then in 1994 shipped to Finnminerals in Finland for pilot tests. Tests included were beneficiation from grinding, flotation, and micro-ionizing. Tests were also conducted on the chemical and physical properties of the talc, particle size distribution and paper-grade rheology tests. The final product produced included talc filler and extender with an average particle size 10 microns and brightness of 80 to 83 per cent (ISO), and a pitch control with an average particle size of 2 microns and a brightness of 83 to 85 per cent (ISO). A coating-grade, slurry talc pigment was also produced meeting rheological specification of light weight coated (LWC) papers (Assessment Report 23691). These tests were followed-up by LWC paper trial runs where several different weights of coated-grade papers were produced using the talc slurry. The results of some of these tests are summarized as follows:
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Mineralogy Ore Concentrate
talc 56 94.9
chlorite 7 1.7
magnesite 35 3.1
dolomite 2 0.3
sulphides 0.03 0.02
magnetite 0.10 0.03
brightness 56 66
yellowness 15 11
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Composition
Talc Magnesite
SiO2 62.2 MgCO3 78.2
Al2O3 0.04 CaCO3 0.1
MgO 29.4 MnCO3 0.1
FeO 2.6 FeCO3 21.3
NiO 0.22
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The low brightness and high yellowness are caused by the presence of
iron hydroxide minerals, the latter being indicative of surface
weathering.
Possible reserves based on 200 metres length, 150 metres width
and 150 metres depth are 13,000,000 tonnes (Assessment Report 22665).
